This invention relates to a method for preparing a cheese having a closed rind, wherein fresh granular curd after separation from the whey is directly or after a short time subjected to a pressing treatment in a cheese pressing mold until a rind forms and the desired moisture content in the cheese has been achieved.
After the desired acidity has been achieved in the cheese through the action of microorganisms, the cheeses are salted in a brine bath and subsequently ripened.
In the assessment of the quality of the structure of the eventual cheese of the closed-rind type such as Gouda or Edam, the appearance of the section of the cheese at an age of approximately 2 weeks is of essential importance.
This section should be virtually blind, that is, there should not be any irregular holes present. What is allowed, on the other hand, is the occurrence of round, smooth xe2x80x9ceyesxe2x80x9d due to the gas formation of microorganisms during the ripening of the cheese.
Heretofore, it was not possible to produce a cheese without irregular holes from a granular curd. By exposing curd to the air, air adheres to the curd parts. This adsorbed air cannot be removed during a conventional pressing procedure and remains visible in the eventual cheese as holes.
The invention contemplates offering a solution to the problem outlined. To that end, according to the invention, the fresh pre-drained curd parts are poured into a cheese pressing mold, whereafter the curd parts, prior to the pressing treatment, are subjected during a short initial pressing procedure to obtain a blind structure of the cheese in the cheese pressing mold to a vacuum treatment with a substantially constant vacuum depth in the order of approximately 95% or more.
It has been found that the vacuum depth is a critical factor in obtaining the closed structure. At a vacuum depth of approximately 95% (72.5 mm Hg abs.) or more, a closed structure, that is, a structure without or virtually without irregular holes is obtained.
It is noted that from an article by J. Czulak, entitled: xe2x80x9cSimpler Approach to Cheddaringxe2x80x9d, published in Dairy Engineering, June 1962, pp. 183-186, a method is known in which curd is simultaneously exposed to a vacuum and a mechanical pressure. However, this concerns cheese types belonging to the Cheddar group.
In the method, the curd is first xe2x80x9ccheddaredxe2x80x9d, which is a procedure whereby the curd is acidified, as a result of which the structure changes. The curd parts fuse with each other and a fibrous structure is formed. The curd bed thus formed is cut into pieces and subsequently salted, mostly with dry salt.
The salted curd fragments obtained are filled into a pressing mold. These molds can be subjected to a vacuum treatment, whereby the air is extracted from between the curd fragments.
In this known method, a vacuum depth is used which does not go beyond about 25 inch Hg, which corresponds to about 80% vacuum. During the vacuum treatment, the cheeses are pressed for a number of hours; optionally, vacuum pressing may be followed by a normal pressing step.
Further, from U.S. Pat. No. 5,082,681 a method is known for forming cheese blocks from prepared curd using a perforated column, which cheese blocks are subsequently compressed in a cheese pressing mold under sub-atmospheric pressure. The prepared curd is obtained by draining fresh curd of whey to obtain a dry curd. The dry curd is salted, undergoes a cheddaring treatment, stirring treatment, mixing treatment or the like to obtain a prepared curd, which is subsequently fed into a vertical perforated column, a so-called block former. In the column, the curd is compressed under its own weight, while air and whey are removed from the column. At the lower end of the column, a guillotine blade is present, by means of which, at intervals, the lower part of the pillar of curd is cut off for forming a cheese block. The cheese blocks thus obtained are subsequently introduced into a pressing mold under a high vacuum, the gas pressure being in the range from xe2x88x920.9 to xe2x88x921.0 bar. Then the cheese blocks are pressed for 45 to 120 seconds at a high pressure of 4 bar or more to rapidly obtain a rind. During pressing, the gas pressure rises to the atmospheric pressure. The purpose of the briefly applied vacuum is to create a rind in order to obtain a transportable block.
From EP-A-0 069 282, a method is known for preparing e.g. Cheddar cheese, in which a deep vacuum is applied for carrying out a flash cooling technique. During the vacuum, no pressing is carried out.
The invention, by contrast, relates to the preparation of semi-hard cheese types, in which the curd is not cheddared and salted, but the fresh curd parts are separated from the whey and the obtained curd parts are directly, or after a short time, along with some moisture clinging thereto, poured into a cheese pressing mold. For a short time, in the order of 30 minutes or shorter, the filled mold is subsequently held under a deep vacuum, in the order of approximately 95% or deeper. At a less deep vacuum, the cheese does not obtain the desired blind structure. During the vacuum period, or a part thereof, mechanical pressure is applied, which may or may not be done in different steps with different mechanical pressures.
The loose curd parts can be charged into a pressing mold by weight or by volume. After the vacuum pressing procedure, the cheeses are further treated in the traditional manner.
Depending on cheese size, pressing (end pressing) is then done for 15 to 90 minutes, Thereupon, if the acidity has not attained the desired degree yet, the cheeses can rest for a particular time before being salted in a brine bath. After the brining time, the cheeses, depending on the type of cheese, can be packaged in film or ripen naturally in a store, optionally in combination with a surface treatment of the rind.
It is noted that in the article entitled xe2x80x9cThe Influence of Pressing on the Composition and Quality of Gouda Cheesexe2x80x9d by N. H. Robertson et al., South African Journal of Dairy Technology (1973) Vol 5, No. 1, an experiment is described with regard to the manner of pressing Gouda cheese and the influence thereof on the composition and texture of the eventual cheese. In two experiments, pressing under a low vacuum of 50 cm Hg was employed. Any relation with the presence or absence of holes in the section is not mentioned.
Further, in an article entitled xe2x80x9cEffect of vacuum treatment on structure formation of cheeses put into moulds by filling or pouringxe2x80x9d by O. M. Eliseev et al. in Trudy, Vsesoyuznyi Nauchno-issledovatel""skii Institut Maslodel""noi i Syrodel""noi Promyshlennosti, (1978), No. 23, 65-69, 146, an experiment is described in which Dutch-type cheese was exposed to vacuum. It was found that a vacuum treatment prior to pressing has a positive effect on the closure of the surface of the cheese, and leads to a greater hardness and viscosity of the cheese, as well as to a greater firmness of the rind. With regard to the formation of eyes in the cheese, no influence of the vacuum treatment was observed.